SC2: Cutie Cat

Writeup

We are given a valid PNG image of a kitten. A classic for CTF competitions. Using the reverse image search function on google, we find an almost identical image in height/width/size. Using compare cat_with_secrets.png original.png -compose src diff.png we extract the differences:

We observe that in the first 3 rows of pixels, they seems to differ at somewhat regular intervals: